HELCOM RECOMMENDATION 9/2

supersedes HELCOM Recommendation 8/3

Adopted 15 February 1988, having regard to Article 13, Paragraph b) of the Helsinki Convention

RECOMMENDATION CONCERNING MEASURES AIMED AT THE REDUCTION OF DISCHARGES PROM URBAN AREAS BY THE USE OF EFFECTIVE METHODS IN WASTEWATER TREATMENT

THE COMMISSION,

RECALLING Paragraph 1 of Article 6 of the convention on the Protection of the Marine Environment of the Baltic Sea Area, 1974, (Helsinki Convention), in which the Contracting Parties undertake to take all appropriate measures to control and minimize land-based pollution of the marine environment of the Baltic Sea Area,

RECALLING ALSO Paragraph 1 of Annex III of the Helsinki Convention, in which the Contracting Parties agree to treat municipal sewage in an appropriate way so that the amount of organic matter does not cause harmful changes in the oxygen content of the Baltic Sea Area and the amount of nutrients does not cause harmful eutrophication of the Baltic Sea Area,

RECALLING FURTHER Paragraph 3 of Annex III of the Helsinki Convention, in which the Contracting Parties agree to minimize the polluting load of industrial wastes in an appropriate way in order to reduce the amount of harmful substances, organic matter and nutrients,

RECALLING FURTHER HELCOM Recommendation 6/7 concerning the treatment of municipal sewage and industrial wastewater with special emphasis on the reduction of discharges of nutrients,

 RECALLING ALSO HELCOM Recommendation 7/3 concerning the reduction of discharges from urban areas by the development of sewerage systems,

 RECALLING ALSO HELCOM Recommendation 7/5 concerning the reduction of discharges from urban areas by the treatment of stormwater,

 RECOGNIZING the importance of municipal sewage as a source of pollution of the marine environment,

 RECOGNIZING ALSO that in an urban area the sewerage system and the sewage treatment plant must be regarded as a unit when pollution load is dealt with.  For practical reasons, however, this Recommendation covers only the treatment of the amounts of water entering the sewage treatment plant. Concerning pollution load due to sewer overflows this is regulated in a qualitative manner in Recommendation 7/5 e). Work is ongoing to strengthen this by stating specific numbers,

 RECOGNIZING ALSO that some of the Contracting Parties are of the opinion that sufficient knowledge and experience of removing nitrogen from urban wastewater in sewage treatment plants is already available.

DESIRING to limit this pollution by effective treatment of municipal sewage,

RECOMMENDS to the Governments of the Contracting Parties to the Helsinki Convention that:

a)         urban (municipal) wastewater deriving from households (domestic wastewater) or industrial enterprises should be collected and treated before being discharged into water bodies; by-passes may only be used in emergency cases;

b)         domestic sewage or wastewater of similar type which is collected in a central sewerage system and treated in wastewater treatment plants, loaded with more than 10 000 person equivalents, should be treated as soon as possible and not later than 1998 by biological methods or other methods giving equivalent results, so that the treatment should result in (calculated as yearly average values with nitrification  inhibitor, and calculated for total amount of influent sewage)

(i)         at least 90% reduction of BOD ₅; and

(ii)        at most a concentration of BOD ₅ in the effluent of the treatment plant of 15 mg/l;

c)         treatment of domestic sewage or wastewater of similar type at plants serving more than 10 000 person equivalents should result as soon as possible and not later than 1998 in effluent yearly average values of total phosphorus below 1.5 mg P/l;

d)         as a start, each Contracting Party should start research and evaluation projects as soon as possible with the purpose to give a basis for further recommendations for nitrogen removal within three years. The project should, inter alia, include studies of process technology and cost for nitrogen removal to reach the targets:

(i)         12 mg total nitrogen/l in the effluent water or 50% reduction of total incoming nitrogen;

(ii)        8 mg total nitrogen/l in the effluent water or 75 % reduction of total incoming nitrogen;

The results of the research and evaluation projects should be reported at annual seminars held within the auspices of the Helsinki Commission;

e)         the values stated in b) and c) need not be applied plantwise if a similar reduction in the total discharge of BOD₅ and phosphorus as yearly average discharge values in domestic sewage or wastewater of similar type which is collected in central sewerage systems can be documented,

RECOMMENDS FURTHER that reports of actions taken by the Contracting Parties should be reported to the Commission one year after the adoption of this Recommendation according to the format accepted by STC 14 (1987) to the extent the Contracting Parties are able to submit the information requested, and thereafter every five years for b) and c) and within three years for d) according to the revised format to be adopted by the Helsinki Commission.